1. Field of the Invention
The invention relates to an automotive construction machine with a transport device extending beyond the machine frame in the working direction, in particular a road milling machine or surface miner, which has an image display device for displaying an image of the surroundings of the construction machine. Moreover, the invention relates to a method for displaying an image of the surroundings of an automotive construction machine.
2. Description of the Prior Art
The known construction machines have a machine frame, which is carried by a chassis that has front and rear running gears, and a working device arranged on the machine frame for removing the ground, for example for removing defective road layers (road milling machine), or mining mineral resources (surface miner). The working device may have a milling and/or cutting roller. Lifting devices, which can in each case be retracted or extended, are associated with the individual running gears of the construction machine so that the machine frame can be lowered or raised together with the working device in relation to the ground surface, or the incline to the ground surface can be changed. The removed material is conveyed using a transport device to a transport vehicle that travels ahead of the construction machine or follows it. The transport device has a jib extending beyond the machine frame, which jib is pivotably arranged on the machine frame about an axis running perpendicular to the plane of the machine frame. The jib can also be pivoted about an axis running parallel to the plane of the machine frame and transverse to the longitudinal axis of the construction machine. Consequently, the jib can be pivoted to the two sides and also adjusted with respect to height. The jib extends in the working direction a long way forward beyond the machine frame in the case of front loader construction machines and rearward in the case of rear loader construction machines.
The operator of the machine is confronted with the problem that the surroundings of the construction machine can only be seen to a limited extent from the control stand. There is the added difficulty in the case of front loader and rear loader construction machines that the machine operator's view is limited to the front or rear by the transport device which protrudes a long way. Consequently, the operator of a road milling machine cannot see from the control stand objects that are concealed by the transport device in his field of vision. Depending on the position of the driver on the control stand extending over the entire width of the machine and the large pivoting range of the transport device, not only may objects located directly below the transport device be concealed, but also those next to or in front of and behind the transport device.
Because of the limited view, construction machines are known that are equipped with one or more cameras. Known road milling machines have, for example, a camera which records an image of a rearward region of the construction machine, which is displayed on a display unit arranged on the control stand. This makes it easier for the machine operator to reverse the construction machine.
DE 10 2013 002 079 A1 (US 2015/368881) describes a digger, which has a plurality of monitoring cameras, which are arranged on different sides of the machine frame at different heights above the ground surface. The individual cameras, which may be displaceably or rotatably mounted on the machine frame for adjustment, record partial images of the surroundings, said images being joined together by means of an image processing system to form a total image of a specific region of the surroundings.
Devices which assist the driver when parking the vehicle are known for motor vehicles, in particular passenger vehicles. Devices of this type are also called driver assistance systems and supply the driver of the motor vehicle with a complete image of the vehicle surroundings from a virtual point of view which is located above the vehicle. A surround view of this type of the surroundings is also called a bird's eye view.
DE 10 2011 077 143 A1 describes a driver assistance system for motor vehicles, which has a front camera in the radiator grille, a side camera in each of the two outside mirrors and a rear camera on the vehicle rear in the region of the grip recess of the boot lid. The front camera records a front image region and the rear camera records a rear image region, while the side cameras record lateral image regions, which are transformed using a suitable imaging model into a total image composed of four image details. Complete coverage of the entire vehicle surroundings is to be achieved in that the cameras are equipped with an optical system allowing a horizontal opening angle of more than 180° (fish-eye optical system), so that the individual image regions overlap one another.
DE 10 2011 088 332 A1 describes a method for improving object detection in multi-camera systems for motor vehicles. The document deals with the problem of detecting raised objects in critical regions of a total image from a bird's eye view. The method provides the recording of a front and rear and two lateral viewing regions, which are joined together to form a total image from a bird's eye view. The critical regions for the object detection are to be located in the region of the stitching. While in current systems a rigidly implemented and non-changeable stitching is defined within the overlapping region of the images, the known method provides a displacement of the stitching in such a way that the stitching is not located in the region of raised objects. This is to avoid objects being located in the region of the stitching which is critical for object detection.
A method for joining together a plurality of image recordings to form a total image from a bird's eye view is also known from DE 10 2006 003 538 B3. Apart from use in passenger vehicles, the known method is also suitable for use in lorries, omnibuses or construction vehicles.
DE 2014 013 155 A1 describes an image display system for movable working machines such as lorries for transporting earth, wheel bearings or diggers, which allows objects located in the limited field of vision of the vehicle driver to be seen. The image display system also provides a bird's eye view. The type of view depends on a specific state of the working machine, which is detected by sensors. In a preferred embodiment, the movement direction and speed of the working machine are detected as the state of the working machine in order to be able to monitor the spatial relationship between machine and object. For example, an object is not to be indicated if it is located outside the movement region of the machine.
Although occasional references in the documentary prior art can be found to the use of the known driver assistance systems even in construction machines, the known driver assistance systems preferably intended for passenger vehicles or lorries are generally not suitable for the particular requirements, which automotive construction machines with a transport device extending a long way forward, in particular a road milling machine or surface miner, demand of driver assistance systems, as these construction machines and motor vehicles fundamentally differ from one another in that a motor vehicle has neither a working device to remove ground material nor a transport device.
The known solutions for driver assistance systems for displaying a bird's eye view image of the surroundings of a vehicle exclusively use cameras with a viewing direction which is directed away from the vehicle, or cameras with viewing directions which are directed away from one another, i.e. the systems do not provide any cameras that face one another. Thus the opinion has become established that the extensions of the axes of all the cameras counter to the viewing direction are to meet in a common centre. The experts were of the opinion that it was not the machine frame, but the surroundings of the vehicle which were to be detected to allow a complete surround view. Therefore, cameras that point away from the vehicle or from a common centre are provided in all vehicles. This also applies to cameras which are mounted on the attachments of the vehicle, for example on the rear view mirrors of a motor vehicle.